11B.5 The Fate Of The Universe

Question 1

what is the big crunch

Answer 1

a possible future for the universe, in which the universe contracts inward to a single point

Question 2

what is critical density

Answer 2

the density of matter in the universe, below which the universe will keep expanding

Question 3

when will big crunch happen

Answer 3

when the density of our universe reaches above the critical density, since the force of gravity between particle decreases with the square of distance

Question 4

what are the 3 theories to the end of the universe

Answer 4

open universe - it keeps expanding

flat universe - it slows down but never reaches standstill

closed universe - it reaches stand still and starts collapsing (big crunch)

Question 5

what is dark matter

Answer 5

a material in the universe that explains some anomalous behaviors of our galaxies; as yet its nature has not been defined

Question 6

how has dark matter discovered

Answer 6

we found the mass of planets using luminosity, the find the rotational speed of the starts, then we found out that the mass we got from luminosity isn’t enough to keep the planets orbit, so we said the planet has mass that doesn’t show light.

Question 7

what is Einstein’s theory about gravity

Answer 7

objects of such great mass can bend light within space such as lenses

Question 8

what is dark energy

Answer 8

a source of a force that is causing the expansion of the universe to accelerate; its nature has not been identified yet